Heat Exchanger With Parallel Fluid Channels

ABSTRACT

A heat exchanger includes a thermal reservoir, a plurality of grooves formed in the thermal reservoir, and a plurality of fluid tubes. Each of the fluid tubes is disposed in a respective one of the grooves such that it is in thermal contact with the thermal reservoir. In a particular embodiment, the grooves form helices around the outer surface of the thermal reservoir. Additionally, each of the grooves can be formed parallel to the other groove(s) such that each of the process fluid tubes will be disposed in parallel to the other process fluid tube(s). The heat exchanger can also include a heating apparatus and/or a cooling apparatus.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of co-pending U.S. Provisional Patent Application Ser. No. 62/333,715, filed on May 9, 2016 by the same inventors, which is incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates generally to heat exchangers and more particularly to heat exchangers with parallel coiled fluid channels.

Description of the Background Art

Heat exchangers having a coiled fluid pathway are known. Such heat exchangers regulate the temperature of a process fluid as it travels through a coiled tube in contact with a thermal reservoir. The process fluid traveling through the tube is heated or cooled to a desired temperature based in part on the flow rate of the process fluid and the temperature of the thermal reservoir. These heat exchangers are advantageous because they have a small footprint, facilitate fine temperature regulation, and prevent outside contamination.

A problem in heat exchangers having a coiled fluid pathway is the drop in pressure that occurs along the length of the fluid path. In particular, as the tubing coil becomes longer, the pressure drop increases. Excessive pressure drop becomes a problem when the heat exchanger cannot deliver fluid at a sufficient pressure or flow rate to meet specifications. Additionally, compensating for high pressure drop places excessive stress and strain on the expensive pumping components used to pump the process fluid through the heat exchanger. One solution is to connect multiple heat exchangers in parallel. Unfortunately, this solution is very costly and increases the overall device footprint because of the multiple heat exchangers. Temperature consistency across multiple heat exchangers can also be difficult to achieve.

What is needed, therefore, is a heat exchanger that reduces pressure drop of the process fluid through the heat exchanger. What is also needed is a heat exchanger that does so, while maintaining a small footprint and low cost.

SUMMARY

The present invention overcomes the problems associated with the prior art by providing a heat exchanger with a plurality of parallel coiled fluid pathways. The invention facilitates regulating the temperature of a process fluid travelling through the heat exchanger in multiple fluid pathways, while maintaining sufficient fluid pressure upon delivery from the heat exchanger to an associated process.

A heat exchanger includes a generally cylindrical thermal reservoir, a plurality of grooves provided on the thermal reservoir, and a plurality of process fluid tubes adapted to be disposed in respective ones of the plurality of grooves and in thermal contact with the thermal reservoir. In particular, the grooves can define helices around an outer surface of the thermal reservoir and/or can be parallel to each other. Still more particularly, a first one of the grooves is formed contiguously with a second one of the grooves. The number of grooves can be at least two, at least three, etc. Additionally, the plurality of process fluid tubes can be adapted to couple to a process fluid supply, which in a particular embodiment, includes a pump for pumping the process fluid. The heat exchanger can also include a heating apparatus and/or a cooling apparatus.

In a particular embodiment, the cooling apparatus comprises a second generally-cylindrical thermal reservoir that is adapted to couple to the thermal reservoir, a plurality of cooling tube grooves formed on the second thermal reservoir, and a plurality of cooling fluid tubes adapted to be disposed in respective ones of the plurality of cooling tube grooves. Each of the cooling tube grooves can define a helix around an outer surface of the second thermal reservoir. For example, a first one of the plurality of cooling tube grooves can be formed in parallel with a second one of the plurality of cooling tube grooves.

A method for manufacturing a heat exchanger includes the steps of providing a generally-cylindrical thermal reservoir, providing a plurality of grooves on the thermal reservoir, and providing a plurality of process fluid tubes in respective ones of the plurality of grooves and in thermal contact with the thermal reservoir. More particularly, the step of providing the plurality of grooves includes forming a plurality of parallel helical grooves around the thermal reservoir. Even more particularly, the step of providing the plurality of process fluid tubes includes wrapping each of the plurality of process fluid tubes around the thermal reservoir in a respective one of the plurality of grooves. Other particular methods include the steps of providing a heating apparatus and/or a cooling apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described with reference to the following drawings, wherein like reference numbers denote substantially similar elements:

FIG. 1 is a block diagram of a fluid processing system including a heat exchanger having multiple fluid pathways according to the present invention;

FIG. 2 is a perspective view showing the heat exchanger of FIG. 1 according to one embodiment of the invention;

FIG. 3 is an exploded perspective view showing the heat exchanger of FIG. 2;

FIG. 4 is a cross-sectional view of a heat exchanger including two process fluid tubes in parallel according to an embodiment of the present invention;

FIG. 5 is a cross-sectional view of a heat exchanger including three process fluid tubes in parallel according to another embodiment of the present invention;

FIG. 6 is a perspective exploded view of a cooling apparatus according to an embodiment of the present invention;

FIG. 7A is a first perspective view of a bracket according to an embodiment of the present invention;

FIG. 7B is a second perspective view of the bracket of FIG. 7A;

FIG. 7C is a third perspective view of the bracket of FIG. 7A installed on the heat exchanger of FIG. 2; and

FIG. 8 is a flowchart summarizing a method of manufacturing a heat exchanger according to one method of the present invention.

DETAILED DESCRIPTION

The present invention overcomes the problems associated with the prior art, by providing a heat exchanger with multiple fluid pathways in parallel and in thermal contact with a common thermal reservoir. In the following description, numerous specific details are set forth (e.g., the number of fluid pathways) in order to provide a thorough understanding of the invention. Those skilled in the art will recognize, however, that the invention may be practiced apart from these specific details. In other instances, details of well-known fluid handling and temperature-regulating practices and components (e.g., supply and delivery piping, electrical routing and control, temperature sensors, etc.) have been omitted, so as not to unnecessarily obscure the present invention.

FIG. 1 is a block diagram of a fluid system 100 using a temperature-regulated process fluid in a process 102. Process fluid is stored in a fluid reservoir 104, which is supplied with process fluid from a fluid source 106. Fluid reservoir 104 represents any suitable container for storing process fluid that is in use, and fluid source 106 represents a fluid supply line and/or bulk storage. Process fluid from fluid reservoir 104 is pumped by a pump 108 into one or more inlet(s) of a heat exchanger 110, which will be described in more detail below. Heat exchanger 110 regulates the temperature of the process fluid and supplies it to process 102 at a desired temperature, pressure, and flow rate. Process 102 can be any process (e.g., semiconductor processing) that requires a temperature-controlled process fluid (e.g., an etching fluid). Excess process fluid not consumed by process 102 can be returned to fluid reservoir 104.

In the following description, heat exchanger 110 will be described as heating the process fluid. However, in other embodiments, heat exchanger 110 can cool the process fluid or be adapted to selectively heat and cool the process fluid.

The temperature of the process fluid supplied by heat exchanger 110 is affected (at least in part) by the length of the fluid pathway through heat exchanger 110, the flow rate of the process fluid through heat exchanger 110, and the temperature of a thermal reservoir (FIG. 2) of heat exchanger 110. A temperature control unit 112 controls the temperature of the process fluid output by heat exchanger 110 using various mechanisms. In particular, control unit receives temperature data of the process fluid output by heat exchanger 110 via temperature sensor feedback data 114. Such feedback data 114 can be obtained from one or more temperature sensors (e.g., in line somewhere between heat exchanger 110 and process 102). Responsive to this temperature data, temperature control unit 112 can adjust the amount of heat energy delivered by heat exchanger 110 via a control path 116, for example, by increasing or decreasing the duty cycle of heating element(s). Temperature control unit 112 can also adjust the pressure and flow rate of process fluid supplied by pump 108 via a pump control path 118. Note that feedback and control paths are shown by dot-dash lines whereas process fluid paths are shown by solid lines.

As will be described in more detail below, heat exchanger 110 employs multiple process fluid pathways in parallel. Accordingly, heat exchanger 110 reduces the pressure drop between its inlet (pump) side and outlet (process) side, which reduces stress and strain on pump 108.

FIG. 2 shows a perspective view of heat exchanger 110. Heat exchanger 110 includes a thermal reservoir 202, a first process fluid tube 204, a second process fluid tube 206, and a heater 208 (only its electrical leads are shown) disposed in a bore 210 of thermal reservoir 202. Thermal reservoir 202 includes a conductive cylindrical body 212 defining a first helical groove 214 and a second helical groove 216 in a sidewall thereof. As shown in the present embodiment, the second helical groove 216 runs parallel to the first helical groove 214 around cylindrical body 202 and includes the same (or nearly the same) number of turns as first helical groove 214. In the present embodiment, grooves 214 and 216 are machined in parallel in a helical fashion around cylindrical body 212. Finally, thermal reservoir 202 is shown to include a plurality holes 217 (two in this example) formed in its upper surface. Such holes 217 can be used to mount thermal reservoir 202 to tooling, house sensors, etc.

First process fluid tube 204 and second process fluid tube 206 are disposed in first helical groove 214 and second helical groove 216, respectively, such that they are in thermal contact with thermal reservoir 202. First process fluid tube 204 includes a first inlet section 218, a first helical section 220, and a first outlet section 222. Similarly, second process fluid tube 206 includes a second inlet section 224, a second helical section 226, and a second outlet section 228. First helical groove 214 and second helical groove 216 are formed such that first helical section 220 of tube 204 and second helical section 226 of tube 206 will be disposed in thermal contact with grooves 214 and 216, respectively, when installed. This thermal contact enables heat exchanger 110 to regulate the temperature of process fluid in each of tubes 204 and 206. Inlet sections 218 and 224 and outlet sections 222 and 228 facilitate connection of tubes 204 and 206 to pump 108 and process 102, respectively. In the present embodiment, the different sections of tubes 204 and 206 are formed integrally but can be separate sections connected together in other embodiments.

Tubes 204 and 206 define a plurality of parallel fluid pathways of heat exchanger 110. In particular, fluid from pump 108 enters tubes 204 and 206 via inlet ports 230 and 232, circulates therethrough, and then exits to process 102 via outlet ports 234 and 236, respectively. Because helical grooves 214 and 216 are formed in parallel, the helical sections 220 and 226 of tubes 204 and 206 are positioned in parallel and heat the process fluid to the same (or similar) temperature.

The pressure drop of a fluid traveling through a tube depends on various factors, including the inner diameter of the tube and length of the tube. For example, in a cylindrical tube of uniform diameter D, the pressure (head) loss due to viscous effects Δp (Pa) can be characterized by the Darcy-Weisbach equation:

${\Delta \; p} = \frac{f_{D}\rho \; {LV}^{2}}{2\; D}$

where ρ is the density of the fluid (kg/m3); L is the length of the tube; D is the hydraulic diameter of the tube (m), which corresponds to the internal diameter for a tube of circular cross-section; V is the mean flow velocity (m/s), which can be measured experimentally as the volumetric flow rate Q per unit cross-sectional wetted area ; and f_(D) is the Darcy Friction Factor.

Additionally, to express the pressure loss in terms of volumetric flow rate through the tube, the following can be substituted into the Darcy-Weisbach equation for V²:

$V^{2} = \frac{Q^{2}}{A_{w}^{2}}$

where Q is the volumetric flow rate (m³/s) and A_(w) is the cross-sectional wetted area (m²) of the tube. Furthermore, the following can be substituted for the square of the area of a full-flowing tube with circular cross-section:

$A_{w}^{2} = \frac{\pi^{2}D^{4}}{16}$

Thus, by substituting the above equations into the initial Darcy-Weisbach equation, the pressure (head) loss in terms of volumetric flow rate Q for a full-flowing tube with circular cross-section is given as:

$\begin{matrix} {{\Delta \; p} = \frac{8\; f_{D}\rho \; {LQ}^{2}}{\pi^{2}D^{5}}} & (1) \end{matrix}$

The above equation implies that, for a fixed volumetric flow rate, the pressure loss increases linearly with tube length, but decreases with the inverse fifth power of diameter. Thus, while increasing the inner diameter of a tube might also be used to reduce pressure drop through a heat exchanger tube, the inventor has discovered that increasing the inner diameter of the tube has practical limitations due to the minimum bend radius of the tube. In particular, as the inner diameter increases, the minimum bend radius of the tube will also need to increase to prevent kinking. This in turn increases the diameter, footprint, and cost of the cylindrical body of the heat exchanger, which is undesirable. Moreover, as the inner diameter increases, so does tube thickness, which greatly reduces the thermal transfer efficiency between the tube and the thermal reservoir.

In view of these limitations, the inventor has found that employing a plurality of process fluid tubes in parallel provides important advantages. For example, if two tubes are used in parallel to supply the same volumetric flow rate as a single tube, the volumetric flow rate through each of the two tubes would be one-half of the total volumetric flow rate (i.e., Q/2). Assuming all other variables are equal, this results in a pressure loss (for each tube) that is given by:

$\begin{matrix} {{\Delta \; p} = {\frac{8\; f_{D}\rho \; {L\left( \frac{Q}{2} \right)}^{2}}{\pi^{2}D^{5}} = {\frac{8\; f_{D}\rho \; {LQ}^{2}}{4\pi^{2}D^{5}} = \frac{2\; f_{D}\rho \; {LQ}^{2}}{\pi^{2}D^{5}}}}} & (2) \end{matrix}$

Note that the total length of tubing in the two-tube embodiment is approximately the same as the length of a single tube, assuming a thermal reservoir with a predetermined number of windings, and so can still be represented as L. Dividing equation (2) by equation (1) indicates that the pressure loss for each of the two parallel tubes is one-fourth (25%) that of the single tube of equation (1).

For a three-tube embodiment where each tube has the same inner diameter and circular cross-section, the volumetric flow rate through each tube is 1/3 of the total (i.e., Q/3). Assuming all other variables are equal, the pressure drop through each of the three tubes is given by:

$\begin{matrix} {{\Delta \; p} = {\frac{8\; f_{D}\rho \; {L\left( \frac{Q}{3} \right)}^{2}}{\pi^{2}D^{5}} = {\frac{8}{9}*\frac{f_{D}\rho \; {LQ}^{2}}{\pi^{2}D^{5}}}}} & (3) \end{matrix}$

Dividing equation (3) by equation (1) indicates that the pressure loss for each of the three parallel tubes is one-ninth (1/9) that of the pressure drop for the single tube.

In summary, adding more tubes in parallel results in a non-linear, decreasing total pressure drop through the heat exchanger. Thus, the invention provides the advantage that the pressure drop between the inlet and outlet of the heat exchanger tubes is reduced, while at the same time, the overall dimensions and cost of the heat exchanger do not significantly increase.

Various manifold/plumbing designs can be used to transport process fluid to and from heat exchanger 110. For example, a manifold or valve body (not shown) with one inlet coupled to pump 108 and multiple outlets each coupled to one of tubes 204 and 206 can be used. Similarly, a manifold or valve body (not shown) with multiple inlets, each coupled to a tube 204 and 206 can be used at outlet ports 234 and 236.

As mentioned above, heat energy is applied to thermal reservoir 202 by at least one heater 208. In the present embodiment, heater 208 is an electric cartridge heater disposed in bore 210, but other heating apparatuses can be used. In a particular embodiment, thermal reservoir 202 is manufactured from a solid (e.g., stainless steel, aluminum, etc.) and bore 210 is machined into thermal reservoir 202. The duty cycle of heater 208 can be adjusted by temperature control unit 112 via control path 116. For example, if one or more temperature sensors (not shown) detect that the process fluid exiting outlet(s) 234 and/or 236 is too low, then temperature control unit 112 can increase the duty cycle of heater 208. Similarly, if the temperature is too high, then control unit 112 can reduce the duty cycle of heater 208.

While in many embodiments the flow of process fluid through heat exchanger 110 is expected to be constant, in other embodiments the flow of process fluid can be varied. For example, the temperature control unit 112 could adjust the temperature of process fluid exiting heat exchanger 110 by adjusting the flow rate of process fluid from pump 108 via control path 118. For example, if one or more temperature sensors (not shown) detect that the process fluid exiting outlet(s) 234 and/or 236 is too low, then control unit 112 can instruct pump 108 to decrease the flow rate of process fluid so the process fluid spends more time in heat exchanger 110. Conversely, if the temperature is too high, control unit 112 can instruct pump 108 to increase the flow rate.

Because parallel tubes 204 and 206 are used, the length of each tube 204 and 206 that is in contact with thermal reservoir 202 will be approximately half the length of a single tube. Therefore, temperature control unit 112 can control heater 208 and pump 108 as needed to adjust temperature of process fluid exiting heat exchanger 110.

FIG. 3 shows an exploded view of heat exchanger 110, including thermal reservoir 202, first process fluid tube 204, and second process fluid tube 206. Helical sections 220 and 226 of tubes 204 and 206, respectively, are nested together when installed in the helical grooves 214 and 216 formed in thermal reservoir 202. Tubes 204 and 206 can be installed one at a time in their respective grooves 214 and 216. Alternatively, the tubes 204 and 206 can be nested together and then installed as a set in grooves 214 and 216. In the present embodiment, tubes 204 and 206 are straight tubes that are wrapped around thermal reservoir 202 in the appropriate grooves 214 and 216, thereby being bent into the appropriate shape. As another example, the tubes 204 and 206 can be formed with the helical shape.

Heat exchanger 110 provides the advantage that one or more of tube(s) 204 and 206 can be removed, cleaned, and/or replaced as needed. This also enables thermal reservoir 202 to be cleaned apart from tubes 204 and 206. It is also cheaper to replace one or more of tubes 204 and 206, than it is to replace the entire heat exchanger 110, which would be required if tubes 204 and 206 were integral parts of heat exchanger 110.

In a particular embodiment, tubes 204 and 206 are made from a chemically-inert material, such as perfluoroalkoxy (PFA) plastic. PFA tubing is desirable for use in high-purity and/or corrosive applications because of its non-reactivity and relatively high working temperatures (exceeding 250 degrees Celsius). However, tubes 204 and 206 can be made from other materials (e.g., PTFE, etc.) as desired.

FIG. 4 is a cross-sectional view of a heat exchanger 400, utilizing two process fluid tubes in parallel. Heat exchanger 400 includes a thermal reservoir 402, a first process fluid tube 404, a second process fluid tube 406, and a bore 410. Thus, heat exchanger 400 is substantially similar to heat exchanger 110 and is representative of the cross-section taken along line A-A in FIG. 2, except that a heater (e.g., one similar to heater 208) is not shown in bore 410. Thermal reservoir 402 defines two parallel, contiguous, helical grooves 414 and 416 therein, which coil downward around the outside of thermal reservoir 402. (Grooves 414 and 416 are shown in phantom around the back of thermal reservoir 402.) First process fluid tube 404 (labeled “A”) is installed in first helical groove 414 down the length of thermal reservoir 402, and similarly, second process fluid tube 406 (labeled “B”) is installed in helical groove 416 down the length of thermal reservoir 402. In other words, tubes 404 and 406 are wrapped in parallel around thermal reservoir 402 and define two parallel fluid pathways for the process fluid. Bore 410 is shown as extending almost the full length of thermal reservoir 402 and is adapted to receive one or more heating elements (e.g., cartridge heaters, not shown) therein. Finally, while thermal reservoir 402 comprises a solid body in this embodiment and should include cross-hatching from top to bottom between bore 410 and its exterior surface, only a portion of this cross-hatching is shown in FIG. 4 so as not to occlude the other labels and features shown.

It should also be noted that the relative sizes of grooves 414 and 416 and the tubes 404 and 406 depicted in FIG. 4 can be changed as desired. For example, grooves 414 and 416 can be made sufficiently deep for the process fluid tubes 404 and 406 to fit entirely or almost entirely within their respective grooves 414 and 416. Additionally, another thermal regulating apparatus (FIG. 6) and/or a bracket (FIG. 7) can be installed over the tubes 404 and 406 and can function to compress the tubes 404 and 406 within the grooves 414 and 416. Doing so could increase the amount of surface area of the tubes 404 and 406 that is in contact with the grooves 414 and 416, thereby improving thermal transfer therebetween.

Because heat exchanger 400 uses two tubes 404 and 406 in parallel, the pressure drop through heat exchanger 400 in each tube 404 and 406 is reduced as compared to a heat exchanger using a single tube as explained above. Heat exchanger 400 also achieves this reduced pressure drop without increasing the footprint of thermal reservoir 402 or substantially increasing the cost of heat exchanger 400. Finally, volume flow rate can be kept high through heat exchanger 400 because of the two tubes 404 and 406.

FIG. 5 shows a cross-sectional view of a heat exchanger 500, utilizing three process fluid tubes in parallel. Heat exchanger 500 includes a thermal reservoir 502, a first process fluid tube 504, a second process fluid tube 506, a third process fluid tube 508, and a bore 510. Thermal reservoir 502 also defines three parallel, contiguous, helical grooves 514, 516, and 518, which coil downward around the outside of thermal reservoir 502. (Grooves 514, 516, and 518 are shown in phantom around the back of thermal reservoir 502, and therefore, only some cross-sectioning is shown.) First tube 504 (labeled “C”) is disposed in groove 514, second tube 506 (labeled “D”) is disposed in groove 516, and third process fluid tube 508 (labeled “E”) is disposed in groove 518. Thus, tubes 504, 506, and 508 are wrapped in parallel down the length of thermal reservoir 502 and define three parallel fluid pathways for the process fluid. Bore 510 extends the length of thermal reservoir 502 and is adapted to receive one or more heating elements (e.g., cartridge heaters, not shown) therein. Finally, while thermal reservoir 502 comprises a solid body in this embodiment and should include cross-hatching from top to bottom between bore 510 and its exterior surface, only a portion of this cross-hatching is shown in FIG. 5 so as not to occlude the other labels and features shown.

All other variable being constant, the pressure drop through one of tubes 504, 506, and 508 will be less than the pressure drop through one of tubes 404 and 406 (FIG. 4), because the volumetric flow rate through each tube 504, 506, and 508 is reduced, while maintaining the total volume flow rate of the heat exchanger. However, even though heat exchanger 500 has an additional fluid channel as compared to heat exchanger 400 and a lower fluid pressure, the footprint and materials cost of thermal reservoir 502 and thermal reservoir 402 are the same or substantially the same. Accordingly, the number of parallel fluid channels (and grooves) can be customized according to the pressure requirements of a particular application without increasing the device footprint.

Those skilled in the art will recognize that the number of tubes in the heat exchanger (as well as other described elements, even if not explicitly stated) is not an essential element of the present invention. For example, the present invention may be practiced with any number of parallel tubes, each additional tube reducing the pressure drop even further.

In particular embodiments, a heat exchanger of the present invention can also include a cooling apparatus. An exemplary embodiment of a cooling apparatus 600 is shown in FIG. 6. Cooling apparatus 600 includes a bifurcated thermal reservoir 602 comprising a first section 604 and a second section 606. A plurality (in this case two) of parallel grooves 608 and 610 are provided in a helical fashion around the thermal reservoir 602. While grooves 608 and 610 are shown separated, they can be formed contiguously (similar to the grooves in FIGS. 4 and 5) instead. A plurality (e.g., two, three, etc.) of cooling tubes 612 and 614 can then be inserted in grooves 608 and 610 in thermal contact with thermal reservoir 602.

Thermal reservoir 602 is generally-cylindrical and is configured to be disposed over the thermal reservoir 202 of heat exchanger 110 such that the inner surfaces of sections 604 and 606 of thermal reservoir 602 are in thermal contact with the process fluid tubes 204 and 206. Thereafter, cooling tubes 612 and 614 can be installed in each of the parallel helical grooves 608 and 610 in thermal reservoir 602. Cooling fluid can then be pumped through each cooling tube to cool thermal reservoir 602, thermal reservoir 202, and the process fluid tubes 204 and 206.

It should also be noted that thermal reservoir 602 can be sized and/or can include passages (e.g., notches, windows, etc.) to accommodate the paths of process fluid tubes 204 and 206 to and from heat exchanger 110. In this example, the length of thermal reservoir 602 (in the long direction) is less than the corresponding length of thermal reservoir 202 of heat exchanger 110 so that, when installed, thermal reservoir 602 does not interfere with process fluid tubes 204 and 206.

Because cooling fluid can be pumped in parallel through the plurality of cooling fluid tubes 612 and 614 installed in the parallel grooves 608 and 610 of cooling apparatus 600, the pressure drop through each of the cooling tubes 612 and 614 is less than the pressure drop would be through a single, longer cooling tube. Thus, the invention reduces wear and tear on a pump (not shown) for pumping cooling fluid through cooling apparatus 600.

FIGS. 7A-7B show perspective views of a bracket 700 that provides a means for containing and mounting heat exchanger 110 to another support structure (not shown). FIG. 7A shows that bracket 700 is bifurcated and includes a first portion 702 and a second portion 704, which are each formed from a rigid material such as aluminum. First portion 702 and second portion 704 are generally semi-cylindrical in shape, except that first portion 702 defines an upper notch 706 and a lower notch 708, which enable process fluid tubes 204 and 206 to be routed through bracket 700. The sizes of upper and lower notches 706 and 708 will depend on the number and diameters of the tubes used by the heat exchanger.

FIG. 7B further shows that the long edges of first portion 702 and second portion 704 are configured to contact one another to define a tubular shape. In a particular embodiment, bracket 700 can be manufactured from a length of round aluminum tubing and then cut (e.g., sawed) in half lengthwise to form portions 702 and 704. Thereafter, notches 706 and 708 can be formed in first portion 702 (e.g., by sawing, trimming, machining, etc.). The inner diameter of such aluminum tubing can be selected based on the outer diameter of thermal reservoir 202 such that bracket 700 will closely engage heat exchanger 110 and retain its tubing (e.g., tubes 204 and 206) in position. For example, in a particular embodiment, the inner diameter of bracket 700 is sized to be the same as the outer diameter of thermal reservoir 202. Bracket 700 is, thus, easily manufacturable in different sizes.

FIG. 7C shows bracket 700 installed around heat exchanger 110. (In this embodiment, heat exchanger 110 does not employ cooling apparatus 600.) Here, first and second portions 702 and 704 have been placed around heat exchanger 110 and clamped in position using three clamps 710. In this embodiment, clamps 710 are worm-drive screw clamps, but other types of clamps can be used. FIG. 7C also shows how notches 706 and 708 enable tubes 204 and 206 to pass through bracket 700. Because bracket 700 closely fits around tubes 204 and 206 and thermal reservoir 202, bracket 700 also helps retain tubes 204 and 206 in thermal contact with grooves 214 and 216 of thermal reservoir 202 (FIGS. 2-3). Additionally, the assembly shown in FIG. 7C can be mounted to a support structure (not shown) using the same or additional clamps 710, some other suitable clamp(s), or other suitable mounting means coupled to the support structure or to bracket 700.

In FIG. 7C, bracket 700 is shown encasing heat exchanger 110 only. However, bracket 700 can still be used if heat exchanger 110 includes a cooling apparatus 600 (as shown in FIG. 6). For example, bracket 700 can be made with an inner diameter that is sized based on (e.g., to be equal to) the outer diameter of thermal reservoir 602 of cooling apparatus 600, so that bracket closely accepts and contains both heat exchanger 110, cooling apparatus 600, and the associated process fluid tubes 204 and 206 and cooling fluid tubes 612 and 614. In such a case, bracket 700 could include larger or additional notches to allow routing of any cooling fluid tubes 612 and 614 associated with cooling apparatus 600 therethrough.

FIG. 8 is a flowchart summarizing a method 800 of manufacturing a heat exchanger according to the present invention. In a first step 802, a thermal reservoir (e.g., thermal reservoir 202) is provided. In a second step 804, a plurality of parallel helical grooves (e.g., grooves 212 and 214) are provided (e.g., machined) in the thermal reservoir. In a third step 806, a plurality of process fluid tubes (e.g., tubes 204 and 206) are provided that are adapted to be wrapped around the thermal reservoir in the helical grooves.

Method 800 also includes several optional steps as described below. In an optional fourth step 808, a heating apparatus (e.g., a heater 208) is provided that is configured to apply heat to the thermal reservoir (e.g., positioned in a bore 210). In an optional fifth step 810, a cooling apparatus (e.g., cooling apparatus 600) is provided. In an optional sixth step 812, a plurality of parallel helical grooves 608 and 610 is provided (e.g., machined) in the cooling apparatus 600. In an optional seventh step 814, a plurality of cooling fluid tubes 612 and 614, which are configured to be wrapped around the cooling apparatus in respective helical grooves 608 and 610, is provided. In an optional eighth step 816, a mounting bracket (e.g., mounting bracket 700) is provided that is adapted to mount the heat exchanger and optional componentry to a support structure.

The description of particular embodiments of the present invention is now complete. Many of the described features may be substituted, altered or omitted without departing from the scope of the invention. For example, alternate heaters (e.g., a sealed combustion heater, an infrared heater, etc.), may be substituted for the electric cartridge heater of heat exchanger 110. As another example, the helical sections of the tubes of heat exchangers 110, 400 and 500 can be fixed to their respective thermal reservoirs in any manner (e.g., with a thermally-conductive adhesive, grease, etc.), so long as they are in thermal contact with the thermal reservoir. As yet another example, the thermal reservoir can be in other forms than cylindrical (e.g., having a polygonal cross section, generally cubic, etc.). Accordingly, the grooves formed therein, as well as the associated process fluid tubes, can be other than helical in shape (e.g., spiral, alternating straight and curved sections, etc.). These and other deviations from the particular embodiments shown will be apparent to those skilled in the art, particularly in view of the foregoing disclosure. 

We claim:
 1. A heat exchanger comprising: a generally cylindrical thermal reservoir; a plurality of grooves provided on said thermal reservoir; and a plurality of process fluid tubes adapted to be disposed in respective ones of said plurality of grooves and in thermal contact with said thermal reservoir.
 2. The heat exchanger of claim 1, wherein each of said grooves defines a helix around an outer surface of said thermal reservoir.
 3. The heat exchanger of claim 2, wherein said plurality of grooves are parallel to each other.
 4. The heat exchanger of claim 3, wherein a first one of said plurality of grooves is formed contiguously with a second one of said plurality of grooves.
 5. The heat exchanger of claim 1, wherein said plurality of process fluid tubes are adapted to be coupled to a process fluid supply.
 6. The heat exchanger of claim 5, wherein said process fluid supply includes a pump.
 7. The heat exchanger of claim 1, wherein the number of grooves is at least two.
 8. The heat exchanger of claim 1, wherein the number of grooves is at least three.
 9. The heat exchanger of claim 1, further comprising a heating apparatus.
 10. The heat exchanger of claim 1, further comprising a cooling apparatus.
 11. The heat exchanger of claim 10, wherein said cooling apparatus comprises: a second thermal reservoir adapted to be coupled to said thermal reservoir, said second thermal reservoir being generally cylindrical in shape; a plurality of cooling tube grooves formed on said second thermal reservoir; and a plurality of cooling fluid tubes adapted to be disposed in respective ones of said plurality of cooling tube grooves.
 12. The heat exchanger of claim 11, wherein each of said cooling tube grooves defines a helix around an outer surface of said second thermal reservoir.
 13. The heat exchanger of claim 12, wherein a first one of said plurality of cooling tube grooves is formed in parallel with a second one of said plurality of cooling tube grooves.
 14. A method for manufacturing a heat exchanger, said method comprising: providing a generally-cylindrical thermal reservoir; providing a plurality of grooves on said thermal reservoir; and providing a plurality of process fluid tubes in respective ones of said plurality of grooves, said plurality of process fluid tubes being in thermal contact with said thermal reservoir.
 15. The method of claim 14, wherein said step of providing said plurality of grooves includes forming a plurality of parallel helical grooves around said thermal reservoir.
 16. The method of claim 15, wherein said step of providing said plurality of process fluid tubes includes wrapping each of said plurality of process fluid tubes around said thermal reservoir in a respective one of said plurality of grooves.
 17. The method of claim 14, further comprising providing a heating apparatus.
 18. The method of claim 14, further comprising providing a cooling apparatus. 